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Old 03-22-2021, 06:11 PM   #1
ITA
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Default 1988 Volvo 240 - LH2.2 1500 RPM Idle

All, I recently bought the vehicle in the title. I did some basic maintenance, oil change, flame trap, air filter, TB and AMM cleaning, and spark plugs. Speedometer and odometer is out, and the coolant temp gauge is not working. I am onto to figuring out those issues and plan to bypass the coolant board, change the coolant temp sensor, and fixing the odometer gears. Would any of these things affect the high idle I am experiencing? TPS seems to be positioned correctly. It is idling right at 1500 RPM once it has idled a bit (starts at 1700, then goes down). If it matters, it is a manual transmission. Thanks!
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Old 03-22-2021, 07:25 PM   #2
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Temp sensor certainly would. The 'puter thinks it is cold outside.

Vacuum leak another good prospect.
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Old 03-22-2021, 10:24 PM   #3
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Temp sensor certainly would. The 'puter thinks it is cold outside.

Vacuum leak another good prospect.
Thanks for confirming. I am looking at IPD and there is a CTS for fuel injection and dash gauge. Should I go ahead and replace both?
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Old 03-22-2021, 11:03 PM   #4
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For the temp gauge, check the wiring before firing the 'parts cannon'.
You can check resistance on the CTS, it's not complicated.
There are several methods for verifying vacuum leaks.

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Old 03-23-2021, 09:35 AM   #5
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Did you try the idle adjustment knob?
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Old 03-23-2021, 10:07 AM   #6
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Did you try the idle adjustment knob?
Yes, I did, thanks for the input. I tightened it all the all and could get it down to 1200 RPM.
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Old 03-23-2021, 10:07 AM   #7
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Originally Posted by Otto Mattik View Post
For the temp gauge, check the wiring before firing the 'parts cannon'.
You can check resistance on the CTS, it's not complicated.
There are several methods for verifying vacuum leaks.

Thanks I will look into it.
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Old 03-24-2021, 04:07 AM   #8
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Thanks I will look into it.
A failing CTS typically thinks the engine is still cold, and therefore is supplying a richer mixture, ...point being, if the motor is cold it should not start out at 1700rpm's, maybe 1000-1200(?), and then drop down to 750/800-900 range,.. of course 1700 is too high.

When 240240 mentioned the idle screw, I realized that it might be your IAC(V), which happened on one of my cars. I cleaned the IAC to no effect, and finally adjusted the idle w/ a small hose clamp on the IAC inlet hose until I found a replacement. As soon as I installed a replacement IAC it idled perfect.

If it's not the IAC and not vacuum leaks, it's possible someone went bonkers and advanced it too much, and that can make it idle overly fast(altho not sure about 1700?). Do you know how to set the timing/use a timing light ?


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Old 03-24-2021, 04:35 AM   #9
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On LH 2.0 and 2.2 cars, the engine should flare up to ~2000 when the engine first starts, then drop immediately to 750 rpm. Another thing to check is the TPS. Make sure that it clicks each time you move the throttle plate by hand. That said, your problem sounds more like advanced timing or a vacuum leak somewhere. If the TPS intermittently clicks, the idle will pretty much be all over the place, ranging from anywhere between 750 and 2400 rpm.

Yet another thing to look at... AC switch. Needs to be all the way over to "0" to turn off the idle boost function. If it is, there's still the possibility that the flap on the side of the switch isn't depressing the microswitch completely. I've had that occur in the past. With the car running, and the center dash console pulled out enough to reach the wires behind it, pull one of the wires on the left side of the AC switch. If the idle drops to something more reasonable, you've found your problem.
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Old 03-27-2021, 10:31 PM   #10
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Originally Posted by John242Ti View Post
On LH 2.0 and 2.2 cars, the engine should flare up to ~2000 when the engine first starts, then drop immediately to 750 rpm. Another thing to check is the TPS. Make sure that it clicks each time you move the throttle plate by hand. That said, your problem sounds more like advanced timing or a vacuum leak somewhere. If the TPS intermittently clicks, the idle will pretty much be all over the place, ranging from anywhere between 750 and 2400 rpm.

Yet another thing to look at... AC switch. Needs to be all the way over to "0" to turn off the idle boost function. If it is, there's still the possibility that the flap on the side of the switch isn't depressing the microswitch completely. I've had that occur in the past. With the car running, and the center dash console pulled out enough to reach the wires behind it, pull one of the wires on the left side of the AC switch. If the idle drops to something more reasonable, you've found your problem.
Interesting my 2.2 set up never did that. The IAC would bump it up slightly upon starting, but nothing close to 2k. The old IAC stuck around 1500-1700(unaltered)until I finally replaced it.

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Old 04-01-2021, 02:24 PM   #11
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Easy to overlook: is your throttle cable adjusted too tight?
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